Upgrading the Properties of Ceramic-Coated Separators for Lithium Secondary Batteries by Changing the Mixing Order of the Water-Based Ceramic Slurry Components

Abstract

Developing uniform ceramic-coated separators in high-energy Li secondary batteries has been a challenging task because aqueous ceramic coating slurries have poor dispersion stability and coating quality on the hydrophobic surfaces of polyolefin separators. In this study, we develop a simple but effective strategy for improving the dispersion stability of aqueous ceramic coating slurries by changing the mixing order of the ceramic slurry components. The aqueous ceramic coating slurry comprises ceramics (Al2O3), polymeric binders (sodium carboxymethyl cellulose, CMC), surfactants (disodium laureth sulfosuccinate, DLSS), and water. The interaction between the ceramic slurry components is studied by changing the mixing order of the ceramic slurry components and quantitatively evaluating the dispersion stability of the ceramic coating slurry using a Lumisizer. In the optimized mixing sequence, Al2O3 and DLSS premixed in aqueous Al2O3-DLSS micelles through strong surface interactions, and they repel each other due to steric repulsion. The addition of CMC in this state does not compromise the dispersion stability of aqueous ceramic coating slurries and enables uniform ceramic coating on polyethylene (PE) separators. The prepared Al2O3 ceramic-coated separators (Al2O3–CCSs) exhibit improved physical properties, such as high wettability electrolyte uptake and ionic conductivity, compared to the bare PE separators. Furthermore, Al2O3–CCSs exhibit improved electrochemical performance, such as rate capability and cycling performance. The half cells (LiMn2O4/Li metal) comprising Al2O3–CCSs retain 90.4% (88.4 mAh g−1) of initial discharge capacity after 150 cycles, while 27.6% (26.4 mAh g−1) for bare PE. Furthermore, the full cells (LiMn2O4/graphite) consisting of Al2O3–CCSs exhibit 69.8% (72.2 mAh g−1) of the initial discharge capacity and 24.9% (25.0 mAh g−1) for bare PE after 1150 cycles.

Heat-Resistant Lithium-Ion-Battery Separator Using Synchronous Thermal Stabilization/Imidization

“…19 Kennedy et al prepared Al 2 O 3 -coated separators with excellent physical properties and prominent battery performances. 20 Yang et al coated conductive polypyrrolemodified lithium montmorillonite that serves as an effective heat-release layer on a PP separator to increase the thermal stability of batteries even at 80 °C. 21 Inorganic nanoparticle materials do not form self-supporting layers, which limits their ability to enhance the thermal stability of commercial separators.…”

“…Qi et al prepared a stable and highly efficient PP/SiO 2 separator by anchoring the nanoscale SiO 2 layer on both sides of the PP separator with covalent bonding . Kennedy et al prepared Al 2 O 3 -coated separators with excellent physical properties and prominent battery performances . Yang et al coated conductive polypyrrole-modified lithium montmorillonite that serves as an effective heat-release layer on a PP separator to increase the thermal stability of batteries even at 80 °C …”

Mechanical Behavior of Lithium-Ion Battery Separators under Uniaxial and Biaxial Loading Conditions

“…Another issue with polyolefin-based separators is their low thermal stability which could lead to thermal runaway, raising safety concerns in the event of overheating. To enhance their electrochemical properties, separators are coated via inorganic particles such as alumina (Al 2 O 3 ), silica (SiO 2 ), titanium oxide (TiO 2 ), and zirconia oxide (ZrO 2 ) [ 14 , 15 , 16 , 17 , 18 ]. Gong et al [ 15 ].…”

Coalbed Methane Enhancement in Low-Permeability Reservoirs by Hydraulic Fracturing with Coated Ceramsite

“…Compared with quartz sand, ceramsite boasts an improved compressive strength. However, the density of ordinary ceramsite is close to that of quartz sand, which requires the combination of fracturing fluid with high viscosity and flow rate, otherwise the proppant is easily embedded in the formation and can hardly be transported deeper into the fractures, which significantly increases the construction difficulty and cost and limits its wide application . The low density, high strength, and high conductivity of coated ceramsite can support the fractures while also preventing sand release and proppant rejection and mitigating formation damage. − …”